1. Field of the Invention
The present invention relates to a surface coating which may be used to provide microbiological stability to high-moisture foodstuffs. More particularly, this invention relates to forming a clear, gel-like coating on the surface of foodstuffs having an exposed surface which exhibits a water activity above 0.9. The practice of this invention enables distribution and sale of such foodstuffs at ambient temperature.
2. Description of the Prior Art
High-moisture foodstuffs, such as cheese cake, pumpkin pie, custard pie, dessert gels and the like, present exposed surfaces to the air which are highly-susceptible to microbiological contamination. Many of these products, such as fresh-baked goods (e.g., pies and cakes) may be packaged in cardboard boxes which are not air-tight and are thus subject to microbial attack from ambient atmosphere. High-moisture products, such as fruit pies and cheese cake, are subject to spoilage when held at ambient conditions for a period of several days. The use of refrigerated distribution and storage could be used to extend the life of these products but this, of course, increases costs and limits distribution and sale of the product.
The use of glazes or coatings to prevent microbial spoilage of foodstuffs is known in the art. Such coatings, however, have not proven to be satisfactory for use with high-moisture foodstuffs. Coatings for foodstuffs, such as baked goods, must not detract from the appearance or taste of the product, must not dry out and/or crack during the distribution and use cycles of the product and must not cause operational problems in the manufacturing facility as a result of their use.
In an article entitled, "Microbial Stabilization Of Intermediate Moisture Food Surfaces"by J. A. Torres and M. Karel (Journal Of Food Processing And Preservation, Vol. 9, No. 2, p. 107-119), the use of reduced surface-pH and surface concentration of preservative are identified as techniques to improve microbial surface stability. U.S. Pat. No. 4,863,751 to Voss discloses a liquid, shelf-stable, preservative-containing coating for bakery products, U.S. Pat. No. 4,645,674 to Lang et al. discloses a sorbate and acid-containing coating for bakery products. Both of these patented bakery coatings are designed for use on relatively-low A.sub.w bread and roll-type baked goods and neither of these patents disclose the use of gelled coatings. U.S. Pat. No. 4,196,219 to Shaw et al. discloses a process for extending the life of pre-cooked meats, poultry and fish by the application of a coating of an aqueous dispersion of the calcium salt of carrageenan (i.e., iota carrageenan).